Numerous patient beds are known, in which the individual portions or segments are adjustable or pivotable relative to one another. Adjustment may take place manually or else motively. In motive adjustment, the energy for driving the motors has to be conducted via the joints. This makes it difficult to exchange individual bed portions. However, it is precisely the exchange of bed portions which is desirable so that the patient bed can be adapted to different operations and consequently so as to increase the flexibility of the bed system. However, the exchangeability of bed portions also entails the risk that bed portions not intended for interconnection are combined with one another, with the result that either parts of the bed may be damaged or even the patient or the operating personnel is put at risk.